An organic electroluminescence (EL) device is regarded as a promising solid-emitting inexpensive large-area full color display device, and various developments have been conducted so far. In general, an organic EL device comprises an emitting layer and a pair of opposing electrodes that sandwich the emitting layer. When an electrical field is applied between the both electrodes, electrons are injected from the cathode and holes are injected from the anode. Further, these electrons are re-combined with the holes in the emitting layer, create an excited state, and energy is emitted as light when the excited state is returned to the ground state.
Conventional organic EL devices have a problem that they are insufficient in respect of device lifetime. Prolonging the lifetime of an organic EL device is an important subject, and hence, materials for an organic EL devices have been gradually improved in recent years (Patent Documents 1 to 3, for example). However, further prolongation of the lifetime has been demanded.